1. Field of the Invention
The invention relates to a two-stage method of preparing aqueous, autocrosslinking copolymer dispersions based on acrylate copolymers which have acetoacetyl groups and carboxyl groups and which are neutralized with polyamines which act as a crosslinking component, and to their use as binders for storage-stable one-component coating materials and, in combination with low molecular mass polyisocyanates, as binders for two-component coating materials which crosslink at room temperature or at elevated temperature.
2. Description of Related Art
EP 0555774 A1 discloses a one-stage method of preparing such copolymer dispersions. The products, however, have a disadvantage. Firstly, a high proportion of acetoacetyl groups is required in order to achieve a sufficient crosslinking density of the coating films; secondly, this high proportion of appropriate monomers brings about the formation, during the copolymerization, of bits and coagulum which can be removed again only at great length and using complex apparatus.